Cause

During every login, the device would transmits its Device Id to Salesforce. If Salesforce detects the Device Id has changed while the device is still logged in, Error 10012 would occur. This extremely rare case may happen if the device record in Salesforce has been accidentally altered by user or if the Device Id has been altered (for example with an app that can change the Device Id.)

Solution

Avoid performing any more job on the device as those completed jobs may not sync properly.